Videoconferences are currently created using conference bridges as part of a telecommunication network as illustrated in FIGS. 1 to 3.
FIG. 1 illustrates a typical telecommunication network 8 for a videoconference. It includes a multiparty conference bridge 13 with (in this example) three video endsystems (video telephony devices) 11 sending video streams to the conference bridge over the Internet 10 which sends back composite images to the three endsystems. This technique involves each video endsystem creating a connection to the conference bridge and streaming their compressed video to it. The conference bridge then decompresses the incoming video images and through policy or audio-level detection, calculates what arrangement of images should be sent back out to the endsystems. It then resizes, as necessary, the incoming images, constructs a new image which is a composite of the incoming images and compresses it. This process is repeated by the conference bridge for each video endsystem in the conference so that each has a unique composition of the incoming images.
FIG. 2 illustrates a telecommunication network 8 for a videoconference that uses a distributed conference bridge arrangement. In this arrangement, video endsystems (video telephony devices) 23 are connected to their local conference bridge 21 and video endsystems (video telephony devices) 24 are connected to another local conference bridge 22. The bridges connect together 25 via the Internet 10. This arrangement functions in a similar way to the single bridge arrangement of FIG. 1, but with the data processing carried out shared by the conference bridges.
FIG. 3 illustrates a telecommunication network for a small (3-party) videoconference where one of the endsystems (video telephony devices) 30 is used as a conference bridge for the three endsystems (video telephony devices) 30, 31 and 32. This arrangement functions in a similar way to the single bridge arrangement of FIG. 1, but with the data processing carried out by the video end system 30 used as a conference bridge.
These telecommunication networks for video conferencing require one or more conference bridges which perform large amounts of video decompression, scaling, composition and recompression. The processing power of this resource scales with the number of participants or endsystems in the conference requiring their own composition. Thus, none of these prior art conference bridge arrangements scale well. For large-scale multiparty videoconferencing to work, the choice has been to restrict the functionality of the endsystems to simplify the processing task of the bridge, or to increase the power and cost of the bridge to allow participants to keep the functionality they desire. Advantageously, the arrangement of FIG. 3 does not require a separate conference bridge or bridges (like the arrangements of FIGS. 1 and 2 respectively) but maintains the problem of scalability as regards large conferences.